Conventional safety locks having pivotal bolts are provided with a thumb turn on one side of a lock housing and a key turn on the other side of the lock housing. When the lock is installed in a door, the thumb turn is located on the inner surface of the door and the key turn is located on the outer surface of the door. Both the thumb turn and the key turn are capable of moving through an angle of at least 360.degree. before the bolt rotates from a locking to an unlocking position.
In order to open a locked door from the inside of a room, one first determines the direction in which the thumb turn must be rotated and then applies a force on the thumb turn knob in that direction. However, in a pressure situation on might not realize that the thumb turn will only unlock the bolt when turned in the proper direction and panic after rotating the thumb turn in the wrong direction. Also a person under stress might not rotate the thumb turn through an angle of 360.degree. and panic because he felt that the lock was not functioning properly. In cases where the lock does not function properly the small thumb turn does not provide enough leverage for the manual force required to rotate a jammed bolt.
It is therefore an object of this invention to provide a safety lock having a pivotal bolt which can be rotated by both key actuated means and handle means.
It is another object of this invention to provide a safety lock having a pivotal bolt which is rotated from a locking position to an unlocking position by turning a handle means which is restricted to a turning movement of less than 180.degree..
It is a further object of the invention to provide a safety lock in which the direction of the force required on a handle means to rotate a pivotal bolt from locking position to an unlocking position is readily apparent.
It is yet another object of the present invention to provide a safety lock with a handle means having enough leverage to rotate a pivotal bolt, which has jammed, from a locking to an unlocking position.